Pos
Description
1
Scheme grounding point
It is important to insure that only one grounding point exist in this scheme.
2
Three-phase plate with setting resistors and metrosils. Protective ground is a separate 4 mm screw
terminal on the plate.
3
Necessary connection for three-phase metrosil set.
4
Position of optional test switch for secondary injection into the high impedance differential IED.
5
Necessary connection for setting resistors.
6
Factory-made star point on a three-phase setting resistor set.
The star point connector must be removed for installations with 670 series
IEDs. This star point is required for RADHA schemes only.
7
Connections of three individual phase currents for high impedance scheme to three CT inputs in
the IED.
7.2.3.2
Connections for 1Ph High impedance differential protection HZPDIF (87)
GUID-D68A237F-610C-4AF0-870F-273117F64D92 v10
Restricted earth fault protection is a typical application for 1Ph High impedance
differential protection HZPDIF (87). Typical CT connections for the high impedance
based protection scheme are shown in figure
.
1MRK 504 163-UUS A
Section 7
Differential protection
Transformer protection RET670 2.2 ANSI
165
Application manual
Summary of Contents for RELION RET670
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